One or more aspects of this invention generally relates to a hybrid system that has a fuel cell, an electrical motor and an internal combustion engine.
Recently, a hybrid power supply equipment having a combination of a fuel cell and a secondary battery has been developed. The hybrid power supply equipment changes an output of the fuel cell based on increase and decrease of electrical loading. And the hybrid power supply equipment operates the fuel cell in a range under 30% of system efficiency. To resolve this problem, Japanese Application Publication No. 7-240212 proposes an efficient hybrid power supply equipment that operates a fuel cell in a limited range of output, 30% to 40%.
However, in a case of operating the fuel cell in a limited range of output, the hybrid power supply equipment may not implement the electrical loading, because electrical power to be provided to a electrical motor, auxiliaries and so on runs short if an electrical loading of the fuel cell, an electrical loading of an electrical motor or auxiliaries except for the electrical motor to be provided with an electrical power from the fuel cell, exceeds an output capacity of the fuel cell. This problem is common to a hybrid power supply equipment in which an electrical power is provided to an electrical motor directly and a hybrid power supply equipment in which an electrical power is provided to an electrical motor via a battery or the like.
Various aspects of this invention have been made in view of the above-mentioned circumstances. One or more aspects of the invention provide a hybrid system that can implement the electrical loading of the fuel cell whose output range is limited.